壳聚糖包埋皂土树脂提高白葡萄酒蛋白质稳定性

以壳聚糖和皂土为原料,制备了可回收的壳聚糖包埋皂土树脂,并研究了该树脂对白葡萄酒中蛋白质稳定性的影响.结果表明,该树脂在酒精-水混合体系中稳定,可用于白葡萄酒的澄清与稳定.当树脂使用量为1.00g/100mL酒样,温度15.0℃,间隔振荡36h时,葡萄酒稳定.树脂可重复使用3次,再生后仍能提高白葡萄酒的蛋白质稳定性.白葡萄酒经该树脂处理后,蛋白质含量降低约34%,总酚含量降低约30%,而对总糖、还原糖、酒精度和pH值没有显著性的影响.该实验为壳聚糖包埋皂土树脂应用于提高白葡萄酒的蛋白质稳定性提供了参考.     

木瓜蛋白酶处理葡萄酒中非稳定性蛋白的研究

利用木瓜蛋白酶水解白葡萄酒中非稳定蛋白,确定酶反应最佳条件为:在pH 6.5,45 ℃条件下,加木瓜蛋白酶0.6g/mL反应38 h,可有效取出白葡萄酒中非稳定蛋白至0.31 g/L,氨基酸含量升高至6.7 mg/L,显著提高白葡萄酒稳定性.     

白葡萄酒中4种皂土下胶计量实验方法的比较

蛋白质等含氮化合物是造成葡萄酒沉淀的主要原因之一,白葡萄酒尤其明显。为预防已装瓶的白葡萄酒出现蛋白质沉淀,生产中常常经过下胶处理(其中包括皂土下胶)沉淀酒中不稳定的蛋白质。为预防皂土下胶过度或不足,常采用的实验方法有:皂土指示剂(bentotest)法、三氯乙酸(trichloroacetic acid)试剂法、加热法及酒精沉淀法。本实验分别将白葡萄酒通过梯度皂土计量进行下胶处理,然后对4种方法进行测试和比较,从而获得白葡萄酒预期皂土下胶的剂量。结果表明:皂土指示剂与三氯乙酸法所测量的下胶剂量较加热测试法高;加热测试法则更接近自然沉淀条件,6 h加热法比30 min加热处理更适用于热气候地区;在本实验中酒精沉淀测试无法测量下胶剂量。     

稳定葡萄酒中蛋白质的方法

Ｍｏｉｎｅ,Ｖ．ａｎｄＤｕｂｏｕｒｄｉｅｕ,Ｄ．国际专利申请书:ＷＯ９７４９７９４．１９９７．转化酶酿酒酵母的酶消化能生产对白葡萄酒中蛋白质沉淀具有稳定作用的制品,利用葡聚糖酶和蛋白酶作为稳定剂可获取甘露蛋白质（ＭＰ３２）。稳定葡萄酒中蛋白质的方法@连...     

甘露糖蛋白对葡萄酒稳定性的影响

本文研究了甘露糖蛋白对葡萄酒酒石和蛋白稳定性的影响。结果表明,甘露糖蛋白可以提高白葡萄酒的酒石和蛋白稳定性,但对红葡萄酒的酒石稳定性没有明显影响。白葡萄酒中加入甘露糖蛋白后,其饱和温度由12℃降低到8℃;皂土用量由1.5‰减少到0.5‰。     

酵母甘露糖蛋白对葡萄酒酒石稳定性影响的研究

研究了葡萄酒中加入一定量的甘露糖蛋白后，对葡萄酒酒石稳定性的影响。研究证明，甘露糖蛋白对白葡萄酒的酒石稳定具有很好的作用，但对红葡萄酒酒石稳定性无效。发现甘露糖蛋白可以增加葡萄酒的电导率，用极点电导率测试仪检测酒石稳定性，白葡萄酒的电导率下降值减小。甘露糖蛋白加入量过多，会增加非结晶性沉淀的可能性。     

蛋白——21世纪的葡萄酒工艺

法国通过多年研究发现 :“把白葡萄酒与酵母泥一起在酒桶中储存数月 ,可实现酒石酸的稳定性 ,省去了冷处理过程。他们对两种甘露蛋白进行了鉴定 ,一种可改善葡萄酒对蛋白质的稳定性 ,另一种能保证葡萄酒对酒石酸沉淀的稳定和长时间的保护。用甘露蛋白保护葡萄酒的方法将朝着能最大限度地完善葡萄酒质量 ,同时限定操作规程的葡萄酒酿造设想发展。可设想２１世纪酿造葡萄酒方法 :轻微的粘合过滤 ;澄清 ;甘露蛋白处理 ;错流过滤 :无菌灌装 ;瓶装（换桶前膜过滤）。蛋白——21世纪的葡萄酒工艺@李小全     

菠萝蛋白酶对干白葡萄酒蛋白质稳定性的影响

研究菠萝蛋白酶对干白葡萄酒蛋白质稳定性的影响,以新鲜干白葡萄酒为试验材料,添加菠萝蛋白酶,通过测定葡萄酒的浊度、蛋白质稳定性、蛋白质含量,确定其最适添加量、作用温度和作用时间。结果表明,菠萝蛋白酶对两款酒样澄清的最佳添加量分别为2.0 mg/L、2.5 mg/L,温度均为22 ℃,作用时间为24 h。菠萝蛋白酶可澄清干白葡萄酒,明显提高其蛋白质稳定性。     

酵母甘露糖蛋白对葡萄酒冷稳定性作用效果的研究

研究了在葡萄酒中添加不同剂量的酵母甘露糖蛋白后,对葡萄酒后期处理稳定性效果的影响。结果表明,酵母甘露糖蛋白可以增加葡萄酒的电导率,对霞多丽干白葡萄酒的后期处理稳定性具有很好作用。并通过试验筛选加入甘露糖蛋白(200mg/L)对干白葡萄酒冷稳定处理作用中,初始电导率值变化、电导率下降值、K和Ca含量变化的分析研究,对葡萄酒酒石稳定性作用机理进行了初步研究。     

白葡萄酒中蛋白质含量的测定—考马斯亮蓝G—250法

蛋白质以及它的化合物是葡萄酒中的重要成份之一，在酒中它和多肽类参与了产品感观特性和物理特性的构成，但白葡萄酒中过多的蛋白质，会引起葡萄酒的混浊和沉淀。因此在研究和解决葡萄酒的蛋白稳定性问题时，蛋白质的定量测定是很重要的方面。而目前多测定粗蛋白含量，即...     

Degradation of white wine haze proteins by Aspergillopepsin I and II during juice flash pasteurization

Bentonite is commonly used to remove grape proteins responsible for haze formation in white wines. Proteases potentially represent an alternative to bentonite, but so far none has shown satisfactory activity under winemaking conditions. A promising candidate is AGP, a mixture of Aspergillopepsins I and II.; a food grade, well characterized and inexpensive protease, active at wine pH and at high temperatures (60-80°C). AGP was added to two clarified grape juices with and without heat treatments (75°C, 1min) prior to fermentation. AGP showed some activity at fermentation temperatures (≈20% total protein reduction compared to control wine) and excellent activity when combined with juice heating (≈90% total protein reduction). The more heat stable grape proteins, i.e. those not contributing to wine hazing, were not affected by the treatments and therefore accounted for the remaining 10% of protein still in solution after the treatments. The main physicochemical parameters and sensorial characteristics of wines produced with AGP were not different from controls.     

Proteins in white wines: Thermo-sensitivity and differential adsorbtion by bentonite

Protein fractions in a Chardonnay wine (invertases, glucanases, chitinases and thaumatin-like proteins) were identified using 2D-electrophoresis and mass spectrometry. The sensitivity of these fractions to heat-induced denaturation and precipitation following heat-treatments at different temperatures was studied and compared to their affinity for bentonite, a clay used to adsorb proteins and stabilise wines with regards to protein hazes. The different proteins exhibited different sensitivity with regards to heat-induced precipitation, glucanases being the most sensitive and invertases the least. Thaumatines and chitinases were characterised by a wide range of behaviours attributed to structural micro-heterogeneities. Protein depletion upon the addition of increasing bentonite doses was also dependent on the considered fraction. A good correlation was shown between protein affinity for bentonite and their sensitivity to heat precipitation. Results were discussed considering the current winemaking practices used to assess white wine stability and define bentonite doses needed to achieve their stabilisation.     

Effects of fining with different bentonite labels and doses on colloidal stability and colour of a Valpolicella red wine

This study addressed four different labels of activated sodium bentonite during the fining of a young Valpolicella red wine. Preliminary tests determined the bentonite dose (0.15, 0.30 or 0.50 g L^?1) that would achieve colloidal stability, and this dose was further applied during laboratory‐scale trials. The bentonites were characterised by physico‐chemical parameters, and the effects of the label and dose on the wine colloidal stability, proteins, colour indices and phenolic compounds were measured. The results demonstrated that 0.50 g L^?1 for every bentonite label provided colloidal stabilisation without harshly affecting the colour. Unlike to what happens in white wines the least charged bentonite labels were effective at stabilising the red wine colloidal state by partially reducing its protein content. Simultaneously, the most negatively charged clay samples determined the largest depletions on the total polyphenols, anthocyanins, tannins and polymeric pigments. The differentiated action of clays with different surface charge density among white and red wines may be explained by the interaction mediated by positively charged anthocyanins towards either protein or tannin depletion. Although pioneering, these results may move towards the definition of a safe, allergen‐free, and effective adjuvant for colloidal stabilisation targeted to wine type.     

Chemical compounds and mechanisms involved in the formation and stabilization of foam in sparkling wines

The visual properties of sparkling wine including foam and bubbles are an indicator of sparkling wine quality. Foam properties, particularly foam height (FH) and foam stability (TS), are significantly influenced by the chemical composition of the wine. This review investigates our current knowledge of specific chemical compounds and, the mechanisms by which they influence the foam properties of sparkling wines. Grape and yeast proteins, amino acids, polysaccharides, phenolic compounds, organic acids, fatty acids, ethanol and sugar are examined with respect to their contribution to foam characteristics in sparkling wines made with the Traditional, Transfer, and Charmat and carbonation methods. Contradictory results have been identified that appear to be due to the analytical methods used to measure and quantify compounds and foam. Biopolymer complexes are discussed and absent knowledge with regards to thaumatin-like proteins (TLPs), polysaccharides, amino acids, oak-derived phenolic compounds and organic acids are identified. Future research is also likely to concentrate on visual analysis of sparkling wines by in-depth imaging analysis and specific sensory analysis techniques.     

A survey of phenolic compounds in Spanish wines of different geographical origin

 The phenolic composition of red and white wines from four Spanish Appellations of Origin (official classification of Spanish wines) was investigated. Different hydroxybenzoic and hydroxycinnamic acids, catechins, procyanidins, alcohols, stilbenes and flavonols were identified. Additionally, the ketone 2,3-dihydroxy-1-guaiacylpropan-1-one was identified for the first time in red wines aged in oak barrels. The concentration of most of the phenolic compounds quantified was higher in red wines than in white wines, as would be expected from the different methods of vinification and the grape varieties used. These differences could also contribute to differences in the antioxidant ability of these wines. The multivariate analysis applied to the phenolic compounds quantified allowed the relationships among these compounds to be examined and the origin of the wines to be distinguished. Received: 31 May 1999 / Revised version: 16 August 1999     

Protein evolution during the early stages of white winemaking and its relations with wine stability

Background and Aims: Grape proteins are responsible for the appearance of haziness in white wines during storage after bottling. However, only a few studies have approached the analysis of the fate of must proteins throughout the alcoholic fermentation. This study aimed to systematically investigate the daily variations in protein type and content during the fermentation in order to understand its influence on hazing potential and to attain some basic information to improve the practical management of grape proteins involved in the hazing of white wines. Methods and Results: The evolution of total soluble protein and individual protein fractions was studied in samples taken before, during and after alcoholic fermentation of a white grape must. The results were then related to variations in protein instability as measured by the heat test. Both the quantity of soluble protein and the protein instability increased during fermentation and then decreased after 1‐month storage of the wine. Protein composition did not vary during fermentation as assessed by sodium dodecyl sulfate‐polyacrylamide gel electrophoresis and anion exchange chromatography (AEC). However, variations in the relative proportions of the six protein fractions obtainable by AEC were noted in the different samples. The contribution of each AEC protein fraction to wine instability was determined by considering both the intrinsic instability and the relative quantity of each of the individual protein fractions in the wine. It was demonstrated that the grape thaumatin‐like protein VVTL1, as identified by mass spectrometry, showed the largest increase during fermentation and accounted for almost 40% of the heat‐induced haze of the final wine. Moreover, the decreased protein instability noted after one month storage of the wine could be attributed to the stabilizing effect of polysaccharides released by the yeast cells. Conclusions: The quantity and relative proportion of soluble proteins vary during and after the alcoholic fermentation, as does their heat instability in wine. Grape VVTL1, constituting a large proportion of the total proteins in wine, seems to play a major role in protein haze formation. The release of yeast polysaccharides is related to an increased heat stability of total wine protein, despite the increase in the relative proportion of their most unstable component VVTL1. Therefore, the hazing potential of a white wine seems to be affected by variations in the relative proportions of its macromolecular components occurring in the early stages of winemaking. Significance of the Study: This study addressed for the first time the issue of the protein changing during the fermentation of white wine. The results obtained here offer useful information to aid understanding of the contribution of individual proteins to white wine instability, which can be applied for the improvement of the winemaking process.     

Challenging the Limit of Detection for Egg Allergen Detection in Red Wines by Surface Plasmon Resonance Biosensor

The improvement of a surface plasmon resonance (SPR)-based immunoassay for the detection of traces of egg-based fining agents in red wines is herein described. The latter represents an extension of a previously developed direct assay targeted to the detection of ovalbumin (OVA) as marker of the presence of egg white powder residues, a typical fining agent utilized by the winery industry. In this paper, a suitable pre-treatment procedure was optimized for the sensitive detection of OVA at sub-ppm levels in red wines fortified with egg-white powder, by using an immunoassay proved to be reliable for both white and roseé wines. A red wine from Chianti grapes selected as reference matrix was artificially contaminated with egg-white powder before undergoing different sample purification. Several purification strategies were investigated and tested in order to challenge the limit of detection (LOD) obtained with the methods currently in use for egg allergen detection. Finally, the optimized two-step pre-treatment, combining polyvinylpolypyrrolidone-based purification and size exclusion chromatography, enabled to achieve an LOD in red wine as low as 0.2 μg/mL. The optimized SPR-based method met the method performance criteria issued by the International Organization of Vine and Wine (OIV) concerning the minimum sensitivity required for the analyses of potentially allergenic fining agent proteins in wines, confirming the biosensor as promising tool to monitor the residual contamination level of fined red wines.     

Polyphenolic compounds and antioxidant properties of selected China wines

Thirty-seven China wines, produced from different geographical origins, were examined in this study. The antioxidant activity of wines was measured by different analytical methods: oxygen radical absorbance capacity (ORAC), reducing power, 2,2-azino-di-(3-ethylbenzothialozine-sulphonic acid) (ABTS), 2,2-diphenyl-1-picrylhydrazyl (DPPH·), hydroxyl radical-scavenger activity, superoxide radical-scavenger activity, lipid peroxidation and chelating capacity. Furthermore,total phenols, total flavonoids, total flavanols and total anthocyanins of wines were determined. As expected, the red wines had much higher phenolic content and antioxidant capacity than rosé wines or white wines. Among the red wines, Cabernet Sauvignon and Muscat Hamburg, respectively, represented the wines with the highest and lowest phenolic contents and antioxidant capacity. Among the white wines, Italian Riesling had the lowest phenolic content and antioxidant capacity. Taken together, a close relationship between phenolic contents and antioxidant capacity, for all wines, was observed.     

Effect of using bentonite during fermentation on protein stabilisation and sensory properties of white wine

The bentonite use to remove proteins from white wine is a widespread practice that prevents protein haze formation after bottling. However, an excess of bentonite can have negative effects on both the aromatic profile of young white wines and the quality of the foam of sparkling wines. Therefore, the optimisation of bentonite amount to be used and the moment of its application during winemaking to minimise wine quality losses are of great interest for winemakers. This paper analyses how applying an equal bentonite dose at different stages (must clarification; beginning, middle and end of fermentation) on two scales (industrial and pilot) affects the protein content and stability, physical–chemical characteristics, aromatic profile and foam quality of the obtained wines. No important differences in the oenological parameters were observed between industrial and pilot scales, whereas the scale of the experimental treatments affected protein stability, aroma composition and foam quality of the wines.     

Lysozyme in wine: A risk evaluation for consumers allergic to hen's egg

Lysozyme used in wine production could present a risk for consumers allergic to hen's egg. Thus, precautionary labeling of lysozyme on wines has been adopted within the European Community by updating Annex IIIa by Directive 2007/68/EC on November 27, 2007. Since no scientific data is known about the actual amounts and risks of lysozyme in wines, various in vitro efforts and skin prick tests were applied in this study to evaluate the presence of lysozyme in wines and the reactivity of those residues in allergic individuals and to fulfill the claim of updating Annex IIIa announced in Directive 2003/89/EC. Depending on the wine's color (red or white wine) and fining with bentonite, which is known as an important step to remove unstable proteins mainly from white wines, diverse results were obtained concerning the amounts of lysozyme in finished wines and their in vitro and in vivo reactivity in humans allergic to hen's egg.